/Engine/Source/Editor/Sequencer/Public/SequencerKeyCollection.h
Search forwards or backwards for the first key within the specified range
(Optional) the time of the key that matched the range
[TOptional](API\Runtime\Core\IO\TOptional)< [FFrameNumber](API\Runtime\Core\Misc\FFrameNumber) > FindFirstKeyInRange ( const [TRange](API\Runtime\Core\Math\TRange)< [FFrameNumber](API\Runtime\Core\Misc\FFrameNumber) > & Range, EFindKeyDirection Direction ) const